Recipient for containing moist substrate

ABSTRACT

The invention relates to a recipient for containing moist substrate, which recipient comprises a flexible polymer wall having an outer surface and at least one gas exchanging membrane, which gas exchanging membrane is hermetically sealed to the outer surface of the flexible polymer wall along a sealing line. The sealing line defining a hermetically sealed area of the flexible polymer wall. The flexible polymer wall comprises at least one aperture, being provided in this hermetically sealed area of the flexible polymer wall. The recipient further comprises a means for creating an air chamber circumscribed by the hermetically sealed area and the gas exchanging membrane, for preventing moist substrate to contact the gas exchange membrane when the recipient is filled with moist substrate.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a recipient for containing anysubstrate that requires to breathe through the walls of the recipient,such as a moist substrate, or a powder, and more particular torecipients for cultivation of mushroom spawn and/or fungi.

BACKGROUND OF THE INVENTION

In the cultivation of mushroom spawn and fungi, it is known to usecontainers if the form of polymer recipient in order to hold humidsubstrate in which the fungi or mushroom spawn is cultivated.

Oxygen is to be allowed to enter into the recipient, being a bag, inorder to enable the cultivation of the spawn or fungi. As the spawn orfungi is very sensitive for microspore contamination, e.g. contaminationwith germs or bacteria, recipients such as bags made completely from gaspermeable but liquid impermeable membranes are known from EP418323. Suchmaterial however is quite expensive in use.

Alternative recipients are bags comprising a polymer wall, which isprovided with a plurality of openings. The openings are closed by meansof filter membranes, usually gas and liquid permeable fibrous material.As an example, a bag is described in EP85928. This bag has thedisadvantage that it should not be filled above the level of the filtermembrane.

Another alternative recipient, being a bag, is described in EP645078. Apolyester bag is provided with a number of openings, which openings aresealed by gas permeable sealing strips, e.g. a strip provided from spunbonded micro porous polyolefin.

It was found that recipients, such as e.g. the bags of EP645078, inspite of the sealing with a micro porous strip, still suffer fromcontamination with germs, fungi and/or microspores when being filledcompletely with moist substrate.

SUMMARY OF THE INVENTION

The present invention is based on attempts to avoid contamination withgerms, fungi and/or microspores of bags comprising at least one aperturecovered by a gas exchange membrane, which bags are completely filledwith moist substrate as shown e.g. in EP645078. Surprisingly it has beenfound that the risk of contaminating the substrate within the recipientsuch as contaminating the moist substrate with germs, fungi and/ormicrospores could be reduced significantly by avoiding the gas exchangemembrane contacting the substrate in the recipient. It has been foundthat existing bags, allowing the gas exchange membrane to contact thesubstrate, and allowing the membrane to be humidified by the moisture ofthe substrate, frequently allow germs and fungi to contaminate of thesubstrate. Such germs and fungi will grow, even if the substrate isdried in the vicinity of the apertures later on. Preventing the gasexchange membrane to moisten, by avoiding contact between moistsubstrate and gas exchange membrane, prohibits to a large extent thatcontamination migrates through the gas exchange membrane towards themoist substrate.

In a similar way, it was found that when using other recipients, whichhave a flexible polymer wall which is to contact the moist substrate,the risk of contaminating the moist substrate with contamination withgerms, fungi and/or microspores could be reduced significantly byavoiding the gas exchange membrane contacting the moist substrate at theheight, i.e. at the location where the gas exchanging membrane isprovided in the flexible polymer wall.

It is an object of the present invention to provide improved recipient,such as a bag, for containing moist substrate as well as a method ofmaking the same.

It is an advantage of some embodiments of the present invention toreduce the risk on contaminating the moist substrate in the recipient,e.g. a bag, with germs and bacteria. It is an advantage of some of theembodiments of the present invention to provide recipients, e.g. bagswhich can be filled completely with moist substrate, while reduce therisk on such contamination.

It is also an advantage of the present invention that the gas exchangerate of the gas exchanging membrane is kept more stable and constantover time.

It is another advantage of some embodiments of the present inventionthat the recipients, e.g. bags, may be produced very easily and in acontinue process. It is as well an advantage of some embodiments of thepresent invention to provide a recipient, e.g. a bag, which can easilybe stored and stacked when being empty.

The above objective is accomplished by a recipient, e.g. a bag,according to the present invention.

According to a first aspect of the present invention, a recipient, e.g.a bag for containing moist substrate comprises

-   -   a flexible polymer wall having an outer surface and an inner        surface for contacting a substrate,    -   at least one gas exchanging membrane, the gas exchanging        membrane being coupled to said outer surface of said flexible        polymer wall by a hermetical seal along a sealing line. The        sealing line defines a hermetically sealed area of said flexible        polymer wall.

The wall comprises at least one aperture being provided in or adjacentto the hermetically sealed area of the flexible polymer wall. Therecipient further comprises a means for creating an air chambercircumscribed by the hermetically sealed area, the hermetical seal andthe gas exchanging membrane, for preventing the substrate fromcontacting the gas exchange membrane when the recipient is filled withsuch a substrate, thereby bringing the substrate into contact with thehermetically sealed area of the flexible polymer wall at inner surfaceof said flexible polymer wall. The substrate can be a moist substrate.

The polymer wall is a flexible wall and is to contact the substrate atleast along the hermetically sealed area when the recipient is filledwith substrate. The means for creating an air chamber can be providedpurely by the relative dimensions of the polymer wall and the gasexchange membrane, e.g. by creating a are volume between the two. Therecipient or the gas exchange membrane may also comprise additionalrigid walls or elements for e.g. providing additional support to therecipient, e.g. a bag or container, or to assist the recipient, e.g. abag or container, to keep a given form or shape.

The air chamber on the one hand prevents a substrate such as a moistsubstrate from contacting the gas exchange membrane when the recipientis filled with the substrate such as the moist substrate thereby havingthe flexible polymer wall contacting the substrate such as the moistsubstrate along the hermetically sealed area of the flexible polymerwall. The air chamber avoids migration of bacteria and fungi through thegas exchange membrane especially when the gas exchanging membranebecomes moist. The air chamber can also create a chamber in which noactive air circulation is provided. This prevents or reduces the risk ofthe substrate to dehumidify to a too large extent, meanwhile allowing asufficient gas exchange between ambient and moist substrate.

The term “bag” is to be understood as a usually flexible container thatmay be closed for holding, storing, or carrying something. The bag,being a recipient, comprises at least one flexible wall. The bag mayconsist of a flexible wall, provided with gas exchanging membrane asaccording to the present invention.

The flexible polymer wall of the recipient, e.g. bag, may be providedout of polymer foil material such as a sheet of e.g. polyamide (PA),polyester (PES), polypropylene (PP) or polyethylene (PE), such as highdensity polyethylene (HDPE) or low density polyethylene (LDPE). Thethickness of the polymer foil may depend on the volume and the size ofthe recipient, but is usually chosen in the range of 50 μm to 150 μm. Itis understood that the polymer foil is liquid impermeable. The shape ofthe recipient, e.g. bag, may be chosen depending on the volume and thefinal use.

The gas exchanging membrane may be any appropriate filter membrane aspresently known. It may be selected from e.g. polymer woven or nonwovenfabrics, polymer mechanically or thermally bonded nonwoven fabric,polymer or natural fiber filter paper, glass fiber paper, mechanicallyor thermally bonded glass fiber nonwoven fabric, mechanically bondedpolymer or natural fiber nonwoven or any other suitable membrane.Alternatively, the gas exchanging membrane may be micro-perforatedmembrane, i.e. membranes such as a polymer membrane or a membrane madefrom any other suitable material, which membranes are provided withmicro-perforations. Micro-perforations may be perforations having anysuitable shape, e.g. that can be formed easily such as substantiallycircular micro-perforations. A micro-perforation may have an equivalentdiameter of less than 0.5 mm, such as less than or equal to 0.1 mm, e.g.less than or equal to 0.05 mm. The equivalent diameter of amicro-perforation is the diameter of an imaginary circular perforationhaving a surface area equal to the surface area of that particularmicro-perforation.

Micro-perforated membranes can be sufficient to prevent contamination ofthe substrate, especially when the air chamber between the polymer walland the gas exchange membrane is formed as a barrier. The air chamberprovides a stable air layer, which can withhold contaminating to passthrough. Providing two sets of apertures (the micro-perforations in themembrane and the apertures in the wall) and an air layer creates a sortof labyrinth.

According to some embodiments of the present invention, the gasexchanging membrane may be coupled, e.g. hermetically sealed to theouter surface of the flexible polymer wall along the sealing line,thereby providing the hermetical seal.

According to some embodiments of the present invention, the recipientcomprises a filter strip having a first surface and a second surface.The first and second surfaces of the filter strip are to be understoodas being the major surfaces of the filter strip. The filter stripcomprises an elongate flexible polymer material having at least oneopening. The filter strip further comprises the at least a first gasexchanging membrane allowing gas to pass from one of the first andsecond surface of the strip to the other of the first and second surfaceof the strip. The gas exchanging membrane is coupled to the elongateflexible polymer material along a first sealing line. The first gasexchange membrane covers the at least one opening. The first outersurface of the elongate flexible polymer material is coupled to theouter surface of the flexible polymer wall along the sealing line forproviding said hermetical seal.

According to the present invention, the gas exchanging membrane or thefirst outer surface of the elongate flexible polymer material and thewall of the recipient, e.g. bag, are sealed to each other according to asealing line. The sealing may be provided using any appropriatetechnique to provide a liquid and airtight seal. As an example, sealingmay be provided by thermally binding, e.g. heat sealing or welding theflexible polymer wall and the gas exchanging membrane, or by usingadhesive such as by gluing the wall and the gas exchanging membraneusing appropriate glue or double-sided adhesive tape.

According to embodiments of the present invention, an air chamber may becreated, providing an average distance between the gas exchangingmembrane and the hermetically sealed part of the flexible polymer wallpreferably of 0.1 mm or above or in the range such as 0.1 mm to 10 mm,such as 0.12 mm to 10 mm, or 0.2 mm to 10 mm, e.g. 0.2 mm to 5 mm, orfrom 1 mm to 10 mm. The height of the air chamber is usually dependenton the thickness of the spacing means for creating the air chamber.

According to an embodiment of the present invention, the means forcreating an air chamber may comprise at least one fold in the flexiblepolymer wall, being folded according to a fold line. At least a part ofthis at least one fold is located in the hermetically sealed area. Thefold is provided for unfolding when the recipient, e.g. bag, is filledwith the substrate such as the moist substrate, or when the unfoldedpolymer flexible wall is provided to the recipient, which is eitheralready filled or to be filled. For each section according to a planeperpendicular to the fold line, a first and a second intersection pointare provided at the points where the plane and the sealing lineintersect. The line of intersection of the flexible polymer wall and theplane between the intersection points has a length Lw. The line ofintersection of the gas exchanging membrane and the hermetical sealbetween the sealing lines and the plane between these intersectionpoints has a length Lm. In case the gas exchange membrane is sealed tothe flexible polymer wall of the recipient, the gas exchanging membraneprovides Lm. In case the gas exchange membrane is sealed to the flexiblepolymer wall of the recipient by means of an elongate flexible polymermaterial, the gas exchanging membrane and the elongate flexible polymermaterial provides Lm. According to an embodiment of the presentinvention, Lw may be smaller than Lm.

During filling of the recipient, e.g. bag, with a substrate such as amoist substrate, or during use of the polymer wall, the fold will unfoldor will have to be unfolded. Because of the larger length of then lineof intersection of the gas exchanging membrane and the hermetical sealbetween the sealing lines, in which the gas exchanging membrane ispresent, the line of intersection of the gas exchanging membrane and thehermetical seal between the sealing lines will have a too large lengthto exactly match the flexible polymer wall of the recipient, e.g. bag,when the recipient, e.g. bag, is completely filled. The line ofintersection of the gas exchanging membrane and the hermetical sealbetween the sealing lines, hence the gas exchange membrane will bulgeoutwards, away from the recipients wall, so creating an air chamberbetween the gas exchange membrane and the sealed area of the wall in,which at least one aperture is present.

According to some embodiments of the present invention, the gasexchanging membrane may be folded according to a membrane fold, whichmembrane fold may be substantially parallel to the fold located in thehermetically sealed area of the flexible polymer wall.

According to some embodiments of the present invention, the line ofintersection with the hermetically sealed area may have a substantiallyV-shape profile. According to some embodiments of the present invention,the line of intersection of the gas exchanging membrane and thehermetical seal between the sealing lines may have a substantiallyV-shape profile. According to some embodiments of the present invention,the difference Lm-Lw may be in the range of 1 mm to 10 mm, such as inthe range of 2 mm to 10 mm. Preferably the difference Lm-Lw is in therange of 4% to 20% of Lm, more preferred in the range of 4% to 10% ofLm.

According to other embodiments of the present invention, the sealed areamay be provided with a plurality of apertures.

According to other embodiments of the present invention, the means forcreating an air chamber may include a spacing means located between thegas exchanging membrane and the hermetically sealed area of the flexiblepolymer wall.

According to an embodiment of the present invention, the spacing meansmay be a net or gauze, said net or gauze being preferably made frompolymer filaments. The open structure of the net or gauze will allow airor gas to pass easily from the inner side of the recipient, e.g. bag, tothe outer side and vice versa, whereas it prevents the substrate such asthe moist substrate to contact the gas exchange membrane. Preferably thenet or gauze is made water-repellent.

According to embodiments of the present invention, the net or gauze maybe a woven, braided or knitted net or gauze. The net or gauze may beprovided out of polymer filaments such as filaments from e.g. polyamide,polyester, polypropylene or polyethylene. The term thickness is here tobe understood as the thickness of the gauze measures according togenerally recognizes standard norms in textiles. Optionally, the spacingmeans is a non woven. The spacing means may be a water repellentnonwoven.

The spacing means such as e.g. a net, a gauze or a non woven, may have athickness in the range of 0.1 mm or above, e.g. 0.1 mm to 10 mm, such as0.12 mm to 10 mm.

According to an embodiment of the present invention, the spacing meansmay be one or a plurality of polymer protuberances, blobs or polymerribs located between the hermetically sealed area of the flexiblepolymer wall and the gas exchanging membrane.

According to embodiments of the present invention, the protuberances,blobs or ribs may be provided on the hermetically sealed area of theflexible polymer wall or on the gas exchanging membrane. Theprotuberances, blobs or ribs may have a thickness in the range of 0.1 mmto 5 mm, such as in the range of 0.2 mm to 5 mm, such as in the range of1 mm to 5 mm. The thickness of the protuberances, ribs or blobs is to beunderstood as the average distance between two points of theprotuberance, rib or blob, one point contacting the flexible polymerwall and the other point contacting the gas exchange membrane, whichpoints defining an imaginary line being substantially perpendicular tothe flexible polymer wall.

According to embodiments of the present invention, the at least oneaperture is provided between the protuberances, blobs or ribs.

The blobs need not have particular shapes or dimensions, however blobsmay e.g. be studs or may have a substantially hemispherical shape.

According to embodiments of the present invention, the plurality ofpolymer blobs may be in a regular or irregular array, e.g. matrix-likearranged in the hermetically sealed area. According to embodiments ofthe present invention, the at least one aperture is provided betweensaid plurality of blobs. According to embodiments of the presentinvention, the sealed area may be provided with a plurality ofapertures, which are arranged in an array, e.g. matrix-like arrangedbetween the plurality of polymer blobs.

According to embodiments of the present invention, the recipient, e.g.,bag, may comprise a plurality of ribs, which ribs are arrangedsubstantially parallel.

According to an embodiment of the present invention, the spacing meansmay be a plurality of bulges provided in the hermetically sealed area ofthe flexible polymer wall, bulging outwards of the flexible polymer walltowards the gas exchanging membrane.

According to embodiments of the present invention, the plurality ofbulges may be studs, having a circular rectangular, square or any otherappropriate cross section. The plurality of bulges may be arranged in anarray, e.g. matrix-like arranged in the hermetically sealed area.

According to embodiments of the present invention, the at least oneaperture may be provided between the plurality of bulges.

According to embodiments of the present invention, the recipient, e.g.bag, may comprise a plurality of apertures in the hermetically sealedarea, which plurality of apertures are arranged in an array, e.g.matrix-like arranged between the plurality of bulges.

According to embodiments of the present invention, the plurality ofbulges may be line-like bulges.

The bulges may be provided by stamping or pressing a profile into thepolymer wall of the recipient, e.g. bag, in the sealed area by means ofa die.

According to embodiments of the present invention, the bulges may have athickness in the range of 0.1 mm to 5 mm, such as in the range of 0.2 mmto 5 mm, such as in the range of 1 mm to 5 mm. Thickness of a bulge isto be understood as the average distance between the point of the bulgecontacting the gas exchange membrane and the imaginary plane defined bythe flexible polymer wall surface.

According to embodiments of the present invention, the spacing means maybe provided by a raised edge around the aperture or apertures. Theraised edge may be provided at the outer side of the flexible polymerwall in the hermetically sealed area.

Alternatively, the raised edge may be provided by polymer ribs on thegas exchange membrane extending near or along the outer perimeter of thegas exchange membrane.

According to embodiments of the present invention, the at least oneaperture may have any suitable shape, e.g. that can be formed easilysuch as a substantially circular aperture. According to embodiments ofthe present invention, the at least one aperture may have a surface areain the range of 0.18 mm² to 2.00 mm². According to the presentinvention, when a plurality of apertures is provided, each of theapertures may have a surface area in the range of 0.18 mm² to 2.00 mm².

According to some embodiments of the present invention, the recipientmay be a bag or a container.

According to a second aspect of the present invention, the recipient,e.g. bag, according to the present invention may be used for cultivationof mushroom spawn or fungi.

According to a third aspect of the present invention, it was found thatthe recipients according to the first aspect of the present inventionare also useful to contain powder-like substrate, such as ediblepowder-like substrates, e.g. milk powder.

Usually such powders need to be able to exchange gasses with theambient, which may also be referred to as to allow the powder to“breathe”, when the powder is contained in a recipient. The recipientsaccording to the first aspect of the present invention, allow the powderto exchange gas, while it prevents infection of the powder duringstorage due to the presence of the gas exchange membrane. The airchamber as such created between the perforated wall of the recipient andthe filter prevents transfer of germs and fungi present in the ambientair to contaminate the powder-like substrate.

According to a fourth aspect of the present invention, a filter strip isprovided, The filter strip has a circumference and a first and a secondsurface, and comprises a gas exchange membrane. The first and secondsurfaces of the filter strip are to be understood as being the majorsurfaces of the filter strip. The gas exchanging membrane allows gas,such as air or CO₂, to pass from one of the first and second surface ofthe strip to the other of the first and second surface of the strip. Thefirst surface of the strip may be provided with means along thecircumference of the strip, which means facilitates coupling such assealing of the first surface of the strip with a polymer surface, suchas a flexible polymer wall of a recipient, e.g. a bag. Such means maye.g. a means enabling thermal binding of the first surface of the stripwith a polymer surface.

The filter strip comprises an elongate flexible polymer materialcomprising at least one opening and at least a first gas exchangingmembrane coupled to the elongate flexible polymer material along a firstsealing line. The first gas exchange membrane covers the at least oneopening. According to embodiments, the elongate flexible polymermaterial may comprise N openings, N being more than one. The filterstrip comprises N gas exchanging membranes, each allowing gas to passfrom one of the first and second surface of the strip to the other ofthe first and second surface of the strip. The gas exchanging membranesare coupled to the elongate flexible polymer material along N sealinglines, each of the N gas exchange membranes covering one of the Nopenings.

The gas exchanging membrane or membranes may provide only part of thesurface of the filter strip, such as less than 30% of the surface of thefilter strip, such as less than 20% of the surface of the filter strip,e.g. only 10% of the surface of the filter strip or even only 5% of thesurface of the filter strip.

The filter strip can be provided at the outer surface of a flexiblepolymer wall of a recipient, which flexible polymer wall comprises oneor more apertures as set out above. By sealing, e.g. by thermal binding,of the flexible polymer material of the filter strip to the outersurface of the polymer flexible wall an air chamber is formed. To assistin this, the polymer flexible wall can have a spacing means for creatingthe air chamber on its outer surface. For example, the flexible polymerwall may be provided with one or a plurality of polymer blobs or polymerribs. The ribs may optionally be present along the outer perimeter ofthe gas exchange membrane once the filter strip is sealed to theflexible polymer wall. The rib may be provided by a polymer tube ormonofilament which is fixed to the flexible polymer wall. The airchamber between the filter strip and the flexible polymer wall may berealized by providing, e.g. pressing, bulges in the flexible polymerwall of the recipient with whom the filter strip will cooperate. Thespacing means may be a plurality of bulges provided in the hermeticallysealed area of the flexible polymer wall, bulging outwards of theflexible polymer wall towards the gas exchanging membrane being part ofthe filter strip. The plurality of bulges may be studs, having acircular rectangular, square or any other appropriate cross section. Theplurality of bulges may be matrix-like arranged in the hermeticallysealed area.

An at least one aperture may be provided between the plurality ofbulges. The recipient, e.g. bag, may comprise a plurality of aperturesin the hermetically sealed area, which plurality of apertures arearranged in an array, e.g. matrix-like arranged between the plurality ofbulges. The plurality of bulges may be line-like bulges.

The air chamber is circumscribed by the gas exchange membrane of thefilter strip, the hermetical seal provided by the elongate flexiblepolymer material, the sealed area and the sealing line provided betweenfilter strip and flexible polymer wall. The filter strip according tothis fourth aspect of the present invention may be used in the provisionof a recipient according to the first aspect of the present invention.

The air chamber between the filter strip and the flexible polymer wallmay be realized by providing an infill as a spacing means such aspolymer woven or nonwoven fabrics, polymer mechanically or thermallybonded nonwoven fabric, polymer or natural fiber filter paper, glassfiber paper, mechanically or thermally bonded glass fiber nonwovenfabric, mechanically bonded polymer or natural fiber non woven or anyother suitable fabric between the filter strip and the flexible polymerwall.

According to embodiments of the present invention, at least part of theflexible polymer material of the first surface of the filter strip issuitable for being sealed to a support, such as the polymer wall of arecipient or a polymer sheet being suitable to provide recipients. Thefilter strip further comprising a spacing means for avoiding contactbetween the at least first gas exchanging membrane and the support whenthe at least part of the flexible polymer material of the first surfaceof the filter strip is sealed to the support,

The filter strip may be used to provide a recipient according to thefirst aspect of the present invention. The support will in that case bethe flexible polymer wall of the recipient.

Spacing means is synonym for a spacer, which is a means to fulfil thefunction as set out above.

According to embodiments, the first surface of the strip may be providedwith one or a plurality of polymer blobs or polymer ribs. The firstsurface of the strip may be provided with polymer ribs extending alongthe outer perimeter of said gas exchange membrane. Alternatively, thefirst side of the strip may be provided with secondary filter membranecovering the gas exchange membrane at the first surface of the strip.The skilled person understands that spacing means as set out in relationto the first aspect of the present invention may be used to provide thefilter strip according to the fourth aspect of the present invention

The rib may be provided by a polymer tube or monofilament which is fixedto the first surface of the strip.

The polymer tube or monofilament, the plurality of polymer blobs orpolymer ribs, the ribs possibly only along the outer perimeter of thegas exchange membrane, or the second filter membrane, create an airchamber between the outer surface of a support, such as a flexiblepolymer wall and the gas exchange membrane, when the filter strip issealed to the support, e.g. a flexible polymer wall, thereby providing asealing line between the filter strip, hence the gas exchange membraneand the outer surface of the support, e.g. flexible polymer wall. Asealed area is so created in which the support, e.g. the flexiblepolymer, wall may have at least one aperture.

The filter strip according to this fourth aspect of the presentinvention may be used to provide a recipient according to the firstaspect of the present invention.

It is understood that identical features of flexible polymer walls, gasexchange membranes, apertures polymer blobs or ribs, secondary filtermembranes, such as dimensions and materials, may be used to provide thefilter strip.

It is also understood that the filter strip according to the fourthaspect of the invention may be used to provide a hermetically seatedarea comprising one fold provided in the flexible polymer wall accordingto embodiments of the first aspect of the present invention

It is also understood that the filter strip according to the fourthaspect of the invention may be provided on a flexible polymer wall of arecipient, which wall is provided with bulges. The bulges, as set outabove, may create the hermetically sealed air chamber between the gasexchange membrane provided by a filter strip, and the wall.

The filter strip may cover the full length or width of the recipient,especially in case the recipient is a bag. Both ends of the filter stripcan be sealed with the wall of the recipient, e.g. a bag, at the timethe recipient, e.g. bag, is sealed If required, several filter stripscan be provided on one recipient, e.g. one bag.

According to embodiments of the present invention, the circumference ofthe filter strip may be provided by an elongate material. The elongatematerial is sealed to the gas exchange membrane along the outerperimeter of the gas exchange membrane. The sealing between elongatematerial and the gas exchange membrane may be obtained by e.g. weldingsuch as ultrasonic welding or thermal binding, by heat sealing or usingadhesive such as gluing, or any other suitable method to seal the gasexchange membrane and the elongate material. The elongate material maybe a polymer material. The elongate material may also be an adhesivetape.

The term “elongate material” is to be understood as a long narrow pieceof material.

The filter strips cooperating with suitable flexible polymer wall as setout above, create an air chamber between the outer surface of a flexiblepolymer wall and the gas exchange membrane, quite conveniently.

According to a fifth aspect of the present invention, a polymer sheetfor providing polymer recipients is provided. The polymer sheetcomprises

-   -   a flexible polymer wall having a first outer surface,    -   at least one filter strip according to the fourth aspect of the        present invention as set out above.

At least part of the flexible polymer material of the first surface ofthe filter strip is sealed to the outer surface of the flexible polymerwall by a hermetical seal along a sealing line. The sealing line definesa hermetically sealed area of the flexible polymer wall.

The wall comprises at least one aperture being provided in thehermetically sealed area of the flexible polymer wall, wherein thespacing means creating an air chamber circumscribed by said hermeticallysealed area, said hermetical seal and said gas exchanging membrane.

The polymer sheet according to the fifth aspect of the present inventionhas the advantage that the polymer sheet can be produced easily and in acontinuous process. By simply coupling the two outer edges of thepolymer sheet, e.g. thermally binding the edges to form a polymertubular product, being a recipient in the form of a bag and according tothe first aspect of the present invention can be provided.

Returning to the fourth aspect of the present invention, according toembodiments of the present invention, the filter strip further comprisesan elongate flexible polymer sheet covering the at least one opening andbeing sealed to the flexible polymer material at the first side of thefilter strip along a second sealing line. This second sealing lineencompasses the at least one opening. The spacing means is providedbetween the elongate flexible polymer sheet and the at least one gasexchanging membrane. The elongate flexible polymer sheet has at leastone aperture in the area of the elongate flexible polymer sheetencompassed by the second sealing line.

The elongate flexible polymer sheet may be provided with spacing meansidentical to the spacing means which may be provided to the flexiblepolymer wall of the recipient as set out according to the first aspectof the present invention. These spacing means thus constitute thespacing means of the filter strip according to the fourth aspect of thepresent invention.

The elongate flexible polymer sheet may be provided with a plurality ofapertures identical to the apertures, which may be provided to theflexible polymer wall of the recipient in the sealed area as set outaccording to the first aspect of the present invention.

Also the combination and positioning of spacing means and apertures maybe identical as the combination and positioning of spacing means andapertures on the flexible polymer wall of the recipient as set out withregard to the first aspect of the present invention.

According to a sixth aspect of the present invention, a polymer sheetfor providing polymer recipients is provided. The polymer sheetcomprises at least a first flexible polymer wall having an outer surfaceand at least one filter strip comprising an elongate flexible polymersheet as set out above. At least part of the flexible polymer materialof the first surface of the filter strip is sealed to the outer surfaceof the first flexible polymer wall by a hermetical seal along a sealingline, the sealing line extending along one of the elongate sides of thefilter strip. The polymer sheet thus is provided with a filter stripalong one of its longer sides.

According to embodiments of the present invention, the polymer sheetcomprising a second flexible polymer wall having an outer surface. Atleast part of the flexible polymer material of the first surface of thefilter strip is sealed to the outer surface of said second flexiblepolymer wall by a hermetical seal along a sealing line which sealingline extends along the other of the elongate sides of said filter strip.

The polymer sheet has thus a filter strip, which is provided at both itselongate sides with a polymer wall.

By coupling the two polymer walls to each other at their free edges, orby coupling the free end of the first polymer wall to the secondelongate side of the filter strip, a tubular polymer product being arecipient in the form of a bag and similar to the first aspect of thepresent invention can be provided.

An advantage of the use of the filter strip on a recipient or to providea polymer sheet suitable to form a recipient, is that the difference inelasticity of the gas exchange membrane and the flexible polymer wallcan be compensated, in particular due to the presence of the elongateflexible polymer material of the filter strip. Due to the filling of therecipient, the flexible polymer wall elongates to some extent. Gasexchanging membranes may not always elongate similarly, especially sincethe gas permeable membrane elongates usually less than the polymer wall.This different elongation could cause rupture of the gas exchangemembranes, especially at the perimeter of the gas permeable membrane orthe seat between membrane and polymer wall.

The use of a filter strip on a polymer wall has further the advantagethat flexible recipients, such as bags, can easily be produced byproviding the polymer wall, possibly with means for creating an airchamber, and apertures on the one hand , and the filter strip with gasexchanging membranes on the other hand. Both elements can easily becombined, by mounting, fixing such as gluing or welding the polymer walland the filter strip.

In the particular case of the recipient being a bag, one or more filterstrips may extend from the first outer end of the bag to the secondouter end of the bas, all along the length of the flexible polymer wall,which may e.g. be a flexible polymer tube.

Particular and preferred aspects of the invention are set out in theaccompanying independent and dependent claims. Features from thedependent claims may be combined with features of the independent claimsand with features of other dependent claims as appropriate and notmerely as explicitly set out in the claims.

Although there has been constant improvement, change and evolution ofdevices in this field, the present concepts are believed to representsubstantial new and novel improvements, including departures from priorpractices, resulting in the provision of more efficient, stable andreliable devices of this nature.

The above and other characteristics, features and advantages of thepresent invention will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings, whichillustrate, by way of example, the principles of the invention. Thisdescription is given for the sake of example only, without limiting thescope of the invention. The reference figures quoted below refer to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematically view of an embodiment of the presentinvention in the form of a bag.

FIG. 1 b and FIG. 1 c is a detail of the bag of FIG. 1 a.

FIG. 2 is a schematically view of an alternative embodiment of thepresent invention in the form of a bag.

FIG. 3 a is a schematically view of another embodiment of the presentinvention in the form of a bag.

FIG. 3 b is a view of a cross section according to BB′ of the bag ofFIG. 3 a.

FIG. 4 a, FIG. 4 b and FIG. 4 c are schematically views of alternativeembodiments of the present invention in the form of bags n.

FIG. 5, FIG. 6, FIG. 7 a and FIG. 7 b are a cross sections according toCC′ of the bag of either FIG. 4 a or FIG. 4 b.

FIG. 8 shows a cross section of an alternative embodiment of the presentinvention in the form of a bag, which cross section is made along aplane similar to CC′.

FIG. 9 a and FIG. 9 b are schematically views of an alternativeembodiments of the present invention in the form of recipients.

FIG. 10 schematically shows, in top view and according to a crosssection according to the plane DD, a filter strip as part of a recipientaccording to an embodiment of the present invention.

FIG. 11 a to FIG. 11 c schematically show different filter stripsaccording to embodiments t of the present invention.

FIG. 12 schematically shows an alternative filter strip according to anembodiment of present invention used to provide a recipient.

FIG. 13 schematically shows an alternative filter strip according to anembodiment of the present invention.

FIGS. 14 and 15 schematically show polymer sheets according to anembodiment of the present invention.

In the different figures, the same reference signs refer to the same oranalogous elements.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims. The drawings described areonly schematic and are non-limiting. In the drawings, the size of someof the elements may be exaggerated and not drawn on scale forillustrative purposes. The dimensions and the relative dimensions do notcorrespond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order. It is to be understood that the terms so used areinterchangeable under appropriate circumstances and that the embodimentsof the invention described herein are capable of operation in othersequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other orientations than described orillustrated herein.

It is to be noticed that the term “comprising”, used in the claims,should not be interpreted as being restricted to the means listedthereafter; it does not exclude other elements or steps. It is thus tobe interpreted as specifying the presence of the stated features,integers, steps or components as referred to, but does not preclude thepresence or addition of one or more other features, integers, steps orcomponents, or groups thereof. Thus, the scope of the expression “adevice comprising means A and B” should not be limited to devicesconsisting only of components A and B. It means that with respect to thepresent invention, the only relevant components of the device are A andB.

Similarly, it is to be noticed that the term “coupled”, also used in theclaims, should not be interpreted as being restricted to directconnections only. Thus, the scope of the expression “a device A coupledto a device B” should not be limited to devices or systems wherein anoutput of device A is directly connected to an input of device B. Itmeans that there exists a path between an output of A and an input of Bwhich may be a path including other devices or means.

The invention will now be described by a detailed description of severalembodiments of the invention. More in particular, the invention will beexplained by means of an embodiment of a recipient being a bag. It isunderstood that other recipients having a flexible polymer wall tocontact moist substrate can be provided using the same features as willbe described for the flexible polymer wall of the bags hereafter bedescribed.

It is clear that other embodiments of the invention can be configuredaccording to the knowledge of persons skilled in the art withoutdeparting from the true spirit or technical teaching of the invention,the invention being limited only by the terms of the appended claims.

In a first embodiment of the present invention as shown schematically inFIG. 1 a, a tubular bag 100 is provided with a wall 101 made from apolymer foil. At both sides 102 and 103, the wall 101 comprises a foldaccording to a fold line 140. At each side 102 and 103, a gas exchangingmembrane 120 is hermetically sealed to the outer surface 104 of the wall101 along a sealing line 131, thereby providing a hermetical seal 130between gas exchanging membrane 120 and flexible polymer wall 101. Thesealing line 131 defines a hermetically sealed area 132. In the sealedarea 132, a plurality of apertures 134 is provided in the wall. The gasexchanging membrane 120 is also provided with a membrane fold accordingto a membrane fold line 142, which membrane fold line 142 issubstantially parallel to the fold line 140 of the wall 101 present inthe sealed area 132.

Because of the fold line 140, for each plane perpendicular to the foldline 140 intersecting with the hermetically sealed area, an intersectionline 150 is obtained with the sealed area 132. The intersection line 150extends between two intersection points 152, being the points ofintersection of this plane with the sealing line 131, which points areclosest to the hermetically sealed area. The intersection line 150 has asubstantially V-shape profile between the two intersection points 152.The intersection line 150 has a length Lw between the two intersectionpoints 152.

Similarly for the gas exchanging membrane 120, because of the fold line142, for each plane perpendicular to the fold line 140 intersecting withthe gas exchanging membrane 120, an intersection line 151 is obtainedwith the gas exchanging membrane which has a substantially V-shapeprofile between the two intersection points 152. The intersection line151 has a length Lm between the two intersection points 152. Lm islonger than Lw.

In order to provide a bag, the bag at its lower outer end 160 is closedin order to close liquid tight the wall 101 at this side of the bag.Also measures are taken to hermetically seal the sealed area 132 alongthe zones 162 by sealing the gas exchanging membrane to the wall at eachside 102 and 103 of the outer end 160 along zones 162.

Similarly, at the upper side 170, measures are taken to hermeticallyseal the sealed area 132 along the zones 172, by sealing the wall andthe gas exchanging membrane at each side 102 and 103 along the zone 172of the upper outer end 170. Such measures can be taken prior to fillingthe bag 100 with moist substrate, or after filling the bag 100. Suchmeasures may be the sealing of the bag itself, together with the zones172, by e.g. gluing or welding the wall along the outer end 170, and thewall together with the gas exchanging membrane along zones 172.

In FIG. 1 b, a detail A of side 102 is shown schematically when the bag100 is empty.

In FIG. 1 c the detail A of side 102 is shown schematically when the bag100 is filled As shown in FIG. 1 c, the fold 140 is unfolded; this isangle between the legs of the V-shape profile increases. Seen the lengthdifference between Lw and Lm, the gas exchanging membrane 120 bulgesoutwards of the wall, and creates an air chamber 110 between the sealedarea 132 and the gas exchanging membrane 120. The distance 190 betweenthe two fold lines 140 and 142 of the bag in empty state may be chosenin the range of 1 to 5 mm, such as in the range of 1 to 3 mm. Preferablythe difference Lm-Lw is in the range of 4% to 20% of Lm, more preferredin the range of 4% to 10% of Lm. The difference Lm-Lw is preferablychosen in the range of 1 mm to 10 mm.

As an example according to the embodiment as shown in FIG. 1 a to 1 c,the wall 101 is provided from a PP-, HDPE- or LDPE-foil having athickness of 50 μm or 150 μm. To both sides 102 and 103, a gasexchanging membrane is provided from any suitable material such asTYVEC® 1057D, TYVEC® 1073D, TYVEC® 1443R or TYVEC® 1473R from DuPont.The gas exchanging membrane was folded according to a fold line,providing a V-shape profile to the gas exchanging membrane, which bothlegs have a length of about 25 mm. A gas exchanging membrane was gluedto each of the sides of the bag along a sealing line 131 therebyproviding the hermetical seal 130 between gas exchanging membrane 120and flexible polymer wall 101 The sealing line was located at theborders of the gas exchanging membrane and had a width 181 of about 3 mmto 5 mm.

The sealed area was provided between the sealing lines according to aV-shaped profile. The fold line of the gas exchanging membrane and thefold line of the wall in the sealed area are provided substantiallyparallel. For each plane parallel to the fold line 140, the distancebetween two intersection points 152 along the sealed area is two timesthe length 185 of a leg which length 185 is 20 mm. The length of theintersection line along the sealed area Lw is thus 40 mm.

The distance between two intersection points 152 along the gasexchanging membrane 120 is two times the length 180 of a leg whichlength 180 is 22 mm The length of the intersection line along the gasexchanging membrane Lm is thus 44 mm.

The difference between Lw and Lm is thus 4 mm or 9.09% of Lm.

The distance 190 between the fold line of the wall and the fold line ofthe membrane is about 2 mm when the bag is in empty state.

When this alternative bag is filled with moist substrate, the distance192 between the fold line of the wall and the fold line of the membraneis about 9.2 mm.

In an alternative embodiment, Lm is chosen in such a way that thedistance 190 between the fold line of the wall and the fold line of themembrane is about 4 mm when the bag is in empty state. Lm is thus about48 mm. The difference of Lm-Lw is about 8 mm or 16.6% of Lm When the bagis filled with moist substrate, this substrate contacting the inner sideof the polymer wall of the bag along the hermetically sealing area, thedistance 192 between the fold line of the wall and the fold line of themembrane is about 13.3 mm.

In the hermetically sealed area 132, a plurality of circular aperturesare provided, having a diameter of about 0.5 mm to 1.6 mm, and a surfacearea of about 0.18 mm² to 2.00 mm². The apertures are matrix-likearranged in the sealed area 132, with a density of about 1.5 to 4apertures per cm².

It is clear for a skilled person that other gas exchanging membranes maybe used to provide alternative bags as shown in FIG. 1 a to FIG. 1 c.Similarly, alternative polymer foils, dimensions of the V-shape profilesof the sealed area and the gas exchanging membranes, and the number,shape and distribution of apertures may be used to provide alternativeembodiments.

A bag may be provided with one or two gas exchanging membranes, oralternatively with more than two gas exchanging membranes, as shown inFIG. 2. A tubular bag 200 is provided with a wall 201 made from apolymer foil. At both sides 202 and 203, the wall 201 is provide withsix folds, three at each side of the tube a fold according to a foldlines 241, 242, 243, 244, 245 and 246. Along the folds extendingoutwards from the bag, this is 241 and 243 at the first side 202, and244 and 246 at the second side 203, a gas exchanging membrane is providein a similar way as shown and described in FIG. 1 b and FIG. 1 c.Possibly, however not shown in FIG. 2, also the inwards folds 242 and245 may be provided with a gas exchanging membrane being sealed along asealing line to define a sealed area in which at least one aperture isprovided. The gas exchanging membrane plied according to a fold line isprovided, which fold is pointing outwards from the bag.

Such bag has as an advantage over the bag as shown in FIG. 1 a to FIG. 1c, that the volume of the bag, is larger. Also, a better distribution ofthe exchanged gas is obtained because the apertures are more distributedalong the wall. The bag once filled has a more cube-like shape, whichenables more easily storing.

Another embodiment of a bag 300 as subject of the present invention isschematically shown in FIG. 3 a. A cross section along a plane BB′ isshown in FIG. 3 b.

The polymer foil of the bag 300 provides a wall 305. The moist substrateis to contact the inner side of the polymer wall of the bag along thehermetically sealing area when the bag is filled. The wall 305 isprovided with an aperture 310. At the outer surface 306, a gasexchanging membrane 320 is provided, covering the aperture 310 and beingsealed along a sealing line 312 providing the hermetically sealed area313 and a hermetical seal 314 between gas exchanging membrane 320 andflexible polymer wall 305. The polymer wall and the gas exchangingmembrane are identical as the ones used for the embodiment described inFIG. 1 and FIG. 2.

Along the edge of the aperture 310 the wall is provided with a spacingmeans 330, being a raised edge. The gas exchanging membrane 320 isforced outwards and spaced from the wall 305. Between gas exchangingmembrane 320 and wall, an air chamber 340 is created. When the bag 300is filled with moist substrate, the moist substrate 360 will not extendinto the air chamber, if the aperture is not too big. The maximum sizeof the aperture 310 depends on the type of substrate used to fill thebag. Alternatively the aperture is covered with a secondary filtermembrane, which is then allowed to be moistened, or with an airpermeable stopper means, preventing the moist substrate to leave thepolymer flexible wall, such as e.g. a very open woven gauze or nonwoven. The height 390 of the air chamber 340 is preferably in the rangeof 0.2 mm to 10 mm such as in the range of 1 mm to 10 mm, e.g. in therange of 0.2 mm to 5 mm or such as in the range of 1 mm to 5 mm

Alternatively the raised edge may be replaced by any other form ofprotuberance such as a polymer rib provided to the gas exchangingmembrane along the outer perimeter of the gas exchange membrane. The ribmay be provided in an identical position as the raised edge in FIG. 3 aand FIG. 3 b, but forms now an integral part with the gas exchangemembrane.

The bag may be provided with a plurality of apertures, each beingcovered by a gas exchanging membrane as shown in FIG. 3 b. It isunderstood that according to the invention, the aperture 310 may bereplaced by a number of smaller apertures, all being located within thearea circumscribed by the raised edge 330.

Several alternative embodiments will hereafter be explained by makinguse of cross sections of a bag according to a plane CC′ as shown in FIG.4 a and FIG. 4 b. In FIG. 4 a, a bag 401 has a wall 405. Moist substrateis to contact the inner side of the polymer wall of the bag along thehermetically sealing area when the bag is filled with moist substrate.The polymer wall and the gas exchanging membrane are identical as theones used for the embodiment described in FIG. 1 and FIG. 2. The wall isprovided with a plurality of apertures 410, in this case being slit-likeapertures in a given direction. Preferably a multitude of slits with ashort length may be provided, all slits being aligned according to aline in the given direction. A gas exchanging membrane 406 is providedcovering the apertures. The gas enchaining membrane is sealed to theouter surface of the wall 405 along a sealing line 420 thereby providinga hermetical seal 421 between gas exchanging membrane 406 and flexiblepolymer wall 405. Within the sealing line, a hermetically sealed area430 is obtained. Between the apertures, a spacing means 440 is provided.The spacing means are line-like spacing means, extending betweenadjacent apertures. The moist substrate 460 is provided at the innerside of the wall 405.

In FIG. 4 b, a bag 402 is provided. The same reference numbers refer tothe same features. The apertures in this embodiment are circularapertures provided within the sealed area in an array, e.g. in amatrix-like arrangement. Between the apertures, a spacing means 440 isprovided, which spacing means are point-like spacing means, which can bearranged in an array, e.g. matrix-like arranged in the sealed area.

In the hermetically sealed area 430, a plurality of circular orline-like apertures may be provided, having a diameter or width of about0.5 to 1.6 mm.

In FIG. 4 c, a bag 403 is provided. The same reference numbers refer tothe same features. The apertures in this embodiment are circularapertures provided within the sealed area 451 in matrix-likearrangement. Between the apertures, a spacing means 440 is provided,which spacing means are point-like spacing means, matrix-like arrangedin the sealed area having a diameter of about 0.5 to 1.6 mm. In thecircular hermetically sealed area 451, a plurality of circular aperturesmay be provided, having a diameter of about 0.5 to 1.6 mm. The pluralityof apertures are in an array, e.g. in a matrix-like arrangement andarranged between the plurality of point-like spacing means. The bag 403may be provided with a plurality of hermetically sealed areas 451, e.g.circular ones.

Several embodiments of the spacing means will hereafter be shown in FIG.5, FIG. 6, FIG. 7 a and FIG. 7 b, making use of the same cross sectionalong a plane CC′ of both bags 401 and 402. The cross sections along theplane CC′ of both bags are similar. Identical reference numbers refer tothe same features as in FIG. 4 a and FIG. 4 b.

In FIG. 5, the spacing means 440 is provided by a plurality of bulges501, which are located between the apertures 410. The bulges may belocal thickenings of the polymer foil. The bulges 501 may have the formof studs having preferably a circular basis, having a diameter of 1 mmto 5 mm.

Alternatively, the bulges may be rectangular, square or any othersuitable form. Such bulges would correspond to the spacing means 440 ofthe bag as shown in FIG. 4 b or FIG. 4 c. Alternatively, the bulges maybe line-like having a width of 1 mm to 5 mm. Such bulges wouldcorrespond to the spacing means 440 the bag as shown in FIG. 4 a.

The bulges may have a thickness 502 in the range of 0.2 mm to 5 mm suchas in the range of 1 mm to 5 mm, such as 3 mm. The bulges 501 space thegas exchanging membrane 406 from the wall 405 in the sealed area 430,creating an air chamber 450 having a height equal to the thickness 502.

The bulges, especially when line-like, may e.g. be provided duringextrusion of the polymer foil as processed subsequently.

In FIG. 6, the spacing means 440 is provided from a plurality of bulges601, which are located between the apertures 410. The bulges 601 may beprovided by a profile of the polymer foil at the outer side 604 whichprofile is obtained by imprinted the profile at the inner side 603 ofthe wall 405 in the sealed area 430. The bulges 601 may have the form ofstuds having preferably a circular basis, having a diameter of 1 mm to 5mm. Such bulges would correspond to the spacing means 440 of the bag asshown in FIG. 4 b of FIG. 4 c. The bulges are matrix-like arranged inthe sealed area. The plurality of apertures are in the form of an array,e.g. matrix-like arranged between the bulges.

Alternatively the bulges may be line-like having a width of 1 mm to 5mm. Such bulges would correspond to the spacing means 440 of the bag asshown in FIG. 4 a.

The bulges may have a thickness 602 in the range of 0.2 mm to 5 mm, suchas in the range of 1 mm to 5 mm, such as 3 mm.

This embodiment has the advantage that the apertures and bulges may beprovided during an additional operational step while providing the bag.The bulges, e.g. in the form of studs or substantially parallel lines,possibly arranged according to quincunx, can be provided by pressing adie to the foil, thereby impressing and providing a profile to the foilsurface. The apertures and bulges can be provided by pressing one die(for both punching apertures and impressing profile) to the foil surfaceor by using two consecutive, separate dies (one punching the apertures,the other die impressing the foil) acting on the foil surface. Thebulges 601 space the gas exchanging membrane 406 from the wall 405 inthe sealed area 430, creating an air chamber 450 having a height equalto the thickness 602.

In FIG. 7 a, the spacing means 440 is provided by a plurality of blobsor ribs 701 of polymer material, which are located between the apertures410. The blobs or ribs are provided at the outer surface 704 of thepolymer foil. The blobs 701 may have a circular basis with a diameter of1 mm to 5 mm. Such blobs would correspond to the spacing means 440 ofthe bag as shown in FIG. 4 b. The blobs are in an array, e.g.matrix-like arranged in the sealed area.

Alternatively the spacing means may be line-like ribs having a width of0.5 mm to 5 mm. Such ribs would correspond to the bag as shown in FIG. 4a.

The plurality of apertures are in an array, e.g. matrix-like arrangedbetween the blobs or the ribs.

The blobs or ribs may have a thickness 702 in the range of 0.2 mm to 5mm such as in the range of 1 mm to 5 mm, such as 3 mm. As analternative, shown in FIG. 7 b, the blobs or ribs may be provided at theinner surface 710 of the gas exchanging membrane instead of beingprovided on the inner side of the wall. The blobs or ribs 701 space thegas exchanging membrane 406 from the wall 405 in the sealed area 430,creating an air chamber 450 having a height equal to the thickness 702.

A further embodiment of a bag as subject of the present invention isschematically shown in FIG. 8. A wall 405 and a gas exchanging membrane406 are assembled in substantially similar way as shown in FIG. 4 a orFIG. 4 b. The polymer wall and the gas exchanging membrane are identicalas the ones used for the embodiment described in FIG. 1 and FIG. 2.However, instead of the spacing means 440 being line-like spacing meansas shown in FIG. 4 a or point-like spacing means as shown in FIG. 4 b, agauze 801 is provided between the gas exchanging membrane 406 and thewall 45 in the sealed area 430 of the bag. A gauze 801 from polymermonofilaments 802 is provided, e.g. as a woven fabric. The polymermonofilaments are preferably made hydrophobic or water repellent, inorder to avoid moisture being drained from the moist substrate to thegas exchanging membrane 406 due to capillary effects. The thickness 803is preferably in the range of 3 mm to 10 mm. The filaments used toprovide the gauze are made from similar polymer material as used for thebas wall, e.g. PP, PES, PA, HDPE or LDPE. The filaments may have adiameter of about 0.2 mm to 1.0 mm. The gauze 801 spaces the gasexchanging membrane 406 from the wall 405 in the sealed area 430,creating an air chamber 450 having a height equal to the thickness 803.

As an alternative the gauze 801 is replaced by a water repellentnonwoven, preferably having a thickness in the range of 3 mm to 10 mm.The nonwoven is made from polymer staple fibers or filaments, whichfibers or filaments are thermally, mechanically of chemically bond toeach other. The filaments are of much finer diameter (e.g. ranging from1 μm to 200 μm, e.g. 30 μm) as compared to the filaments used for thegauze 801.

An alternative embodiment of a recipient is disclosed in FIG. 9 a andFIG. 9 b. FIG. 9 a and FIG. 9 b disclose a cross section along avertical plane of a recipient 901, being a rigid box 902 out of rigidpolymer construction. The box is filled with moist substrate 903, thebox is provided at the upper side 904 with a flexible polymer wall 905,which is provided with a gas exchanging membrane 906. The gas exchangingmembrane 906 is sealed to the flexible polymer wall 905 along a sealingline 907, so providing a hermetically sealed area 908 and a hermeticalseal 990 between gas exchanging membrane 906 and flexible polymer wall905. In the hermetically sealed area 908, a plurality of apertures 909are provided. The rigid box 902 and the flexible polymer wall arecoupled to each other along the edges 930 of the polymer wall therebypreventing ambient air to enter the box via the edge 930.

In FIG. 9 a, the polymer wall 905 and the gas exchanging membrane 906are provided with a fold according to fold lines 910. When the polymerwall is provided to the recipient 901 to cover the moist substrate,while the polymer wall is contacting the moist substrate along thesealed area 908, the folds are unfolded and an air chamber 911 isprovided between the outer surface of the sealed area and the gasexchanging membrane 906. This air chamber 911 is provided by means ofthe same features as is explained in FIG. 1 a, FIG. 1 b and FIG. 2, as aresult, the moist substrate is prevented to moisten the gas exchangingmembrane and hence contamination of the moist substrate is avoided.

In FIG. 9 b, the polymer wall 905 and the gas exchanging membrane 906are provided with a spacing means 915, which spacing means may be one ofthe spacing means as set out in FIG. 3 a, FIG. 3 b, FIG. 4 a, FIG. 4 b,FIG. 4 c, FIG. 5, FIG. 6, FIG. 7 a, FIG. 7 b or FIG. 8. When the polymerwall is provided to the recipient 901 to cover the moist substrate, anair chamber 921 is provided between the outer surface of the sealed areaand the gas exchanging membrane 906. As a result, the moist substrate isprevented to moisten the gas exchanging membrane and hence contaminationof the moist substrate is avoided.

Turning to FIG. 10, a filter strip according to the fourth aspect of thepresent invention is shown.

In FIG. 10, it is shown how the strip 1700 is combined with a flexiblepolymer wall 1111, in order to provide a recipient 2000 according to thefirst aspect of the present invention.

The filter strip 1700 comprises a first surface 1003, which will beoriented to the outer surface of the polymer wall 1111. The filter striphas a second surface 1004 which will be oriented away from the polymerwall 1111. The filter strip 1700 comprises an elongate flexible polymermaterial 1006 comprising at least one opening 1106. The filter strip1700 comprising at least a first, and in this particular case more thanone gas exchanging membrane 1010 allowing gas to pass from one of thefirst and second surface of the strip to the other of the first andsecond surface of the strip. The gas exchanging membrane 1010 is coupledto the elongate flexible polymer material 1006 along a first sealingline 1107 and covers the at least one opening 1106.

Between the elongate flexible polymer material 1006 of the filter strip1700 and the polymer wall 1111 two substantially parallel ribs 1013 areprovided. Each of the ribs 1013 extend along the outer perimeter of theelongate flexible polymer material 1006. The ribs may be provided as apolymer monofilament or a polymer tube having a diameter sufficientlythick to provide the air chamber when the filter strip is adhered to aflexible polymer wall.

Alternatively a secondary filter membrane is provided against the partof the first surface 1003 provided by the gas exchange membrane. Thefirst surface 1003 of the strip 1700 is provided with means 1020 alongthe circumference 1002 of the strip which improves the sealing abilityof the filter strip to the flexible polymer wall. The means 1020 may bea means facilitating thermal binding, heat sealing, adhesion, etc. Thecoupling of the flexible polymer material and the flexible polymer wallprovides a sealing line 1131 between the filter strip and the polymerwall, hence providing a sealed area with a sealing line 1131,encompassing the apertures 1112 of the polymer wall. The elongateflexible polymer material hence provides a hermetical seal 1130 betweenflexible polymer wall 1111 and the gas exchange membrane 1010 of thefilter strip 1700.

The filter strip is so sealed to the flexible polymer wall that noaperture is to be located outside the hermetically sealed area.

The two ribs now function as a means for creating an air chamber 1115circumscribed by the hermetically sealed area 1114, the hermetical seal1130, the sealing line 1131 and the gas exchanging membrane 1010. Themoist substrate is prevented to contact the gas exchange membrane 1010.

The filter strip is provided and fixed, i.e. sealed to the polymer wallprior to filling the recipient with moist substrate 1113.

The use of such filter strip according to the fourth aspect of thepresent invention has the advantage that during filling and after beingfilled, the polymer wall of the recipient will extend and will beextended, dependent on the amount of substrate provided in therecipient. This extension will elongate the polymer wall to some extent.The gas exchange membranes are usually less extensible than the polymerwall. Using the filter strips according to the present invention, thedifference in elongation of gas exchange membranes and polymer wall iscompensated by the presence, hence the elongation of the elongateflexible polymer material.

It is clear that the provision of one or more openings in the elongateflexible polymer material covered with gas exchanging membranes issufficient for allowing gas to exchange between moist substrate andambient. The gas exchanging membranes are not to be present along allapertures in the polymer wall. It is sufficient that each aperture islinked with a gas exchanging membrane via an air chamber encompassed bya sealed area.

The skilled person understands that in a similar way as for strip 1700,a recipient according to the first aspect can be obtained by combining aflexible polymer wall with a strip according to the fourth aspect, suchas the strips as shown in FIG. 11 a to FIG. 11 c.

FIG. 11 a shows an alternative filter strip 1100 comprising a gasexchange membrane 1010. The strip 1100 has a circumference 1002, a firstsurface 1003 and a second surface 1004. The gas exchanging membraneallows gas to pass from one surface to the other surface, since itcomprises a zone 1005 where the first and second surface are free, i.e.nothing is to contact the first or second surface. The strip 1100comprises an elongate flexible polymer material 1006. The elongateflexible polymer material 1006 has at least one opening 1106. Theopening 1106 is covered by the gas exchanging membrane 1010. The gasexchange membrane and the elongate flexible polymer wall are sealed toeach other along the perimeter 1009 of the gas exchange membrane.

FIG. 11 b shows filter strip 1200 substantially identical to the filterstrip 1100, which strip 1200 comprising a gas exchange membrane 1010.The first surface 1003 of the strip 1100 is provided with means 1020being a coupling or sealing promoter, along the circumference 1002 ofthe strip, this is along the elongate material 1006. The means 1020 canbe an adhesive, an outer layer adapted for heat sealing, etc.

FIG. 11 c shows filter strip 1300 substantially identical to the filterstrip 1100. The first surface 1003 of the strip 1300 is further providedwith a plurality of polymer blobs or polymer ribs, in this particularembodiment a plurality of ribs 1017 which extend in the longitudinaldirection 1501 of the strip. The gas exchanging membrane allows gas topass from one surface to the other surface, as at least the surfacebetween the plurality of ribs are free. The plurality of polymer blobsor polymer ribs, in this particular embodiment a plurality of ribs 1017constitute a spacing means for avoiding contact between the gasexchanging membrane 1010 and a support when the flexible polymermaterial 1006 present at the first surface of the filter strip is sealedto a support, such as a polymer sheet or a flexible polymer wall.Alternative spacing means such as a gauze from polymer monofilamentse.g. as a woven fabric or water repellent nonwoven, may be coupled tothe first side of the filter strip.

The flexible polymer material to provide the elongate flexible polymermaterial of the strip may be similar or identical material as used forthe polymer wall of the recipient according to the present invention.The gas exchanging membrane of the filter strip are similar or identicalmembranes as of the recipient of the present invention.

An alternative use of the filter strip 1700 used to provide a recipient2000 is shown in FIG. 12. Identical references used in FIG. 10 refer toidentical features in FIG. 12.

The flexible polymer wall 1111 of recipient 2000 is replaced by aflexible polymer wall 1211, which is provided with a plurality of bulges1212, identical as the bulges discloses in relation to FIG. 6. Thebulges constitutes the spacing means for spacing the gas exchangemembrane 1010 from the flexible polymer wall 1211, hence to create anair chamber 1115 circumscribed by the hermetically sealed area 1114, thehermetical seal 1130, the sealing line 1131 and the gas exchangingmembrane 1010. The moist substrate is prevented to contact the gasexchange membrane 1010.

The skilled man understands that the filter strip 1700, 1100, 1200 or1300 as shown in FIG. 10 respectively FIG. 11 a, FIG. 11 b and FIG. 11 cand FIG. 12 may be used as alternative for the gas exchange membranes asshown in FIGS. 1 a, 1 b, 1 c, 2, 3 a, 3 b, 4 a, 4 b, 4 c, 5, 6, 7 a, 7b, 8, 9 a and 9 b. The elongate flexible polymer material of the filterstrip is used to couple, e.g. seal the filter strip to the flexiblepolymer wall of the recipient. By this coupling, the elongate flexiblepolymer material provide a hermetical seat between the gas exchangingmembrane and the flexible polymer wall of the recipient. This couplingmay be obtained by using adhesives or by thermal binding or any othersuitable coupling technique. This coupling provides the hermetical sealalong the sealing line. It is understood that, according to the presentinvention, the apertures in the flexible polymer wall of the recipientare to be encompassed by a sealing line.

FIG. 13 shows an alternative filter strip 13000 comprising a gasexchange membrane 13010. The strip 13000 has a circumference 13002, afirst surface 13003 and a second surface 13004. The gas exchangingmembrane allows gas to pass from one surface to the other surface, sinceit comprises a zone 13005 where the first and second surface are free,i.e. nothing is to contact the first or second surface. The strip 13000comprises an elongate flexible polymer material 13006. The elongateflexible polymer material 13006 has at least one opening 13106. Theopening 13106 is covered by the gas exchanging membrane 13010. The gasexchange membrane and the elongate flexible polymer wall are sealed toeach other along the perimeter 13009 of the gas exchange membrane.

The first surface 13003 of the strip 13000 is further provided with aplurality of polymer blobs or polymer ribs, in this particularembodiment a plurality of ribs 13017 which extend in the longitudinaldirection 13501 of the strip. The gas exchanging membrane allows gas topass from one surface to the other surface, as at least the surfacebetween the plurality of ribs are free. The plurality of polymer blobsor polymer ribs, in this particular embodiment a plurality of ribs 13017constitute a spacing means for avoiding contact between the gasexchanging membrane 13010 and a support when the flexible polymermaterial 13006 present at the first surface of the filter strip issealed to a support, such as a polymer sheet or a flexible polymer wall.Alternative spacing means such as a gauze from polymer monofilamentse.g. as a woven fabric or water repellent nonwoven, may be coupled tothe first side of the filter strip.

FIG. 13 thus shows a filter strip 13000 having a first surface 13003 anda second surface 13004. At least part of the flexible polymer material13006 present at the first surface 13003 of the filter strip 13000 issuitable for being sealed to a support, e.g. a polymer sheet or apolymer wall of a recipient.

The spacing means avoids contact between the gas exchanging membrane andthe support when the flexible polymer material of the first surface ofthe filter strip is sealed to the support.

The filter strip 13000 further comprising an elongate flexible polymersheet 13100 covering the opening and being sealed to the flexiblepolymer material at the first side of the filter strip along a secondsealing line 13102 encompassing the opening. The spacing means isprovided between the elongate flexible polymer sheet and the gasexchanging membrane. The elongate flexible polymer sheet is providedwith a plurality of apertures 13201 in the area 13200 of the elongateflexible polymer sheet encompassed by the second sealing line.

Turning to FIG. 14, a polymer sheet 14000 is shown. The polymer sheetcomprises a flexible polymer wall 14010 having a first outer surface14011 and a filter strip 14020, being a filter strip as shown in figurelie comprising a spacing means 14030. At least part of the flexiblepolymer material 14022 of the first surface 14021 of the filter strip issealed to the outer surface 14011 of the flexible polymer wall 14010 bya hermetical seal 14040 along a sealing line 14041. The sealing linedefines a hermetically sealed area 14042 of the flexible polymer wall14010.

The wall comprises aperture 14045 being provided in the hermeticallysealed area of the flexible polymer wall. The spacing means, in thisparticular case a number of polymer ribs, creates an air chamber 14060circumscribed by the hermetically sealed area, the hermetical seal andthe gas exchanging membrane 14025 of the filter strip 14020. The polymersheet has two outer edges 14100 and 14200. When these outer edges arebrought to each other (as indicated by arrow 14300) and coupled, e.g.sealed to each other, a tubular structure is obtained which can be usedto provided recipients, more particular bags. This may be done bycutting the tubular product into defined lengths and seal the outer endsof the tubular products. A recipient according to the first aspect ofthe present invention is so obtained.

Turning to FIG. 15, a polymer sheet 15000 is shown. The polymer sheetcomprises a flexible polymer wall 15010 having a first outer surface15011 and a filter strip 15020 identical to the filter strip as shown inFIG. 13. At least part of the flexible polymer material 15021 of thefirst surface 15022 of the filter strip 15020 is sealed to said outersurface 15011 of the first flexible polymer wall by a hermetical seal15030 along a sealing line 15031. The sealing line extends along one ofthe elongate sides 15100 of said filter strip 15010.

By coupling the free end 15300 of the first polymer wall 15010 to thesecond elongate side 15200 of the filter strip (as indicated with arrow15400), a tubular polymer product being a recipient in the form of a bagmay be provided.

All above-mentioned embodiments of recipients, such as containers orbags, may be used to cultivate mushroom spawn or fungi. The moistsubstrate with the spawn or spores of fungi is brought into the bag. Therecipient or bag is filled completely with such moist substrate. Therecipients or bags, once closed are stored in an appropriate environmentfor cultivating the mushroom spawn or fungi. The recipients or bags assubject of the present invention will allow gas exchange between moistsubstrate and environment, while bacteria and foreign fungi areprevented to migrate through the gas exchanging membrane towards thesubstrate. Once the cultivated product is harvested, the recipients orbags may be disposed. In case of recipients comprising other thanpolymer flexible wall elements, these other elements may possibly becleaned and reused.

It was found that all the above-mentioned embodiments have the advantagethat contact between gas exchanging membrane and moist substrate isprevented even when the bag is filled completely with moist substrate.The gas exchanging membrane is kept dry, which prevents spores of fungiand bacteria to migrate through the gas exchanging membrane towards themoist substrate. As the gas exchanging membrane is kept dry, the rate ofgas exchanged by the gas exchanging membrane is substantially constant.The air chamber is so-to-say an additional barrier between moistsubstrate and ambient.

It was also found that the above-mentioned embodiments that, when usedto contain powder-like substrate which is to exchange gasses or“breathe” during retention in the recipient, benefit of similaradvantages as the moist substrate. Again, the air chamber is so-to-sayan additional barrier between substrate and ambient, preventing thesubstrate to contact the, now possibly more humid gas filter membrane.By avoiding this contact, spores of fungi and bacteria are prevented tomigrate through the gas exchanging membrane towards the substrate.

It is to be understood that although preferred embodiments, specificconstructions and configurations, as well as materials, have beendiscussed herein for devices according to the present invention, variouschanges or modifications in form and detail may be made withoutdeparting from the scope and spirit of this invention.

1. A recipient for containing a substrate, said recipient comprising aflexible polymer wall having an outer surface and an inner surface forcontacting the substrate, at least one gas exchanging membrane, said gasexchanging membrane being coupled to said outer surface of said flexiblepolymer wall by a hermetical seal along a sealing line, said sealingline defining a hermetically sealed area of said flexible polymer wall,said wall comprising at least one aperture being provided in saidhermetically sealed area of said flexible polymer wall, wherein saidrecipient further comprises a means for creating an air chambercircumscribed by said hermetically sealed area, said hermetical seal andsaid gas exchanging membrane, for preventing the substrate to contactsaid gas exchange membrane when said recipient is filled with thesubstrate thereby bringing the substrate into contact with saidhermetically sealed area of said flexible polymer wall at inner surfaceof said flexible polymer wall.
 2. A recipient for containing moistsubstrate according to claim 1, wherein said gas exchanging membrane ishermetically sealed to said outer surface of said flexible polymer wallalong said sealing line for providing said hermetical seal.
 3. Arecipient for containing moist substrate according to claim 1, whereinsaid recipient comprises a filter strip having a first surface and asecond surface, said filter strip comprising an elongate flexiblepolymer material comprising at least one opening, the filter stripcomprising said at least a first gas exchanging membrane allowing gas topass from one of the first and second surface of the strip to the otherof the first and second surface of the strip, said gas exchangingmembrane being coupled to said elongate flexible polymer material alonga first sealing line, said first gas exchange membrane covering said atleast one opening, said first outer surface of said elongate flexiblepolymer material is coupled to said outer surface of said flexiblepolymer wall along said sealing line for providing said hermetical seal.4. A recipient according to claim 1, wherein said means for creating anair chamber comprises at least one fold in said flexible polymer wallbeing folded according to a fold line, at least a part of said at leastone fold being located in said hermetically sealed area, said fold beingprovided for being unfolded when said recipient is filled with thesubstrate, wherein for each section according to a plane perpendicularto said fold line, a first and a second intersection point are providedat the points where the plane and said sealing line intersect, the lineof intersection of said wall and the plane between said intersectionpoints having a length Lw, the line of intersection of said gasexchanging membrane and the plane between said intersection pointshaving a length Lm, said Lw being smaller than Lm.
 5. A recipientaccording to claim 4, wherein said gas exchanging membrane is foldedaccording to a membrane fold, said membrane fold being substantiallyparallel to said fold being located in said hermetically sealed area. 6.A recipient according to claim 4, wherein the line of intersection withsaid hermetically sealed area has a substantially V-shape profile.
 7. Arecipient according to claim 4, wherein the line of intersection withsaid gas exchanging membrane has a substantially V-shape profile.
 8. Arecipient according to claim 4, wherein Lm-Lw is in the range of 1 mm to10 mm.
 9. A recipient according to claim 4, wherein Lm-Lw is in therange of 4% to 20% of Lm.
 10. A recipient according to claim 4, whereinsaid sealed area is provided with a plurality of apertures.
 11. Arecipient according to claim 1, wherein said means for creating an airchamber comprises a spacing arrangement located between said gasexchanging membrane and said hermetically sealed area of said flexiblepolymer wall.
 12. A recipient according to claim 11, wherein saidspacing arrangement comprises a gauze, said gauze being preferably madefrom polymer filaments.
 13. A recipient according to claim 12, whereinsaid gauze comprises a woven, braided or knitted gauze.
 14. A recipientaccording to claim 11, wherein said spacing arrangement comprises a nonwoven.
 15. A recipient according to claim 12, wherein said spacingarrangement means has a thickness in the range of 0.1 mm to 10 mm.
 16. Arecipient according to claim 11, wherein said spacing arrangementcomprises one or a plurality of polymer blobs or polymer ribs locatedbetween said hermetically sealed area of said flexible polymer wall andsaid gas exchanging membrane.
 17. A recipient according to claim 16,wherein said blobs or ribs are provided on said hermetically sealed areaof said flexible polymer wall.
 18. A recipient according to claim 16,wherein said blobs or ribs are provided on said gas exchanging membrane.19. A recipient according to claim 16, wherein the blobs or ribs have athickness in the range of 0.1 mm to 5 mm.
 20. A recipient according toclaim 16, wherein the spacing arrangement comprises a plurality ofpolymer blobs, said plurality of blobs being a matrix-like arranged insaid hermetically sealed area.
 21. A recipient according to claim 20,wherein said at least one aperture is provided between said plurality ofblobs.
 22. A recipient according to claim 20, wherein said sealed areais provided with a plurality of apertures, which plurality of aperturesare matrix-like arranged between the plurality of polymer blobs.
 23. Arecipient according to claim 16, wherein said spacing means comprises aplurality of ribs, said ribs being substantially parallel arranged. 24.A recipient according to claim 11, wherein said spacing means comprise aplurality of bulges provided in said hermetically sealed area of saidflexible polymer wall, bulging outwards of the polymer flexible polymerwall towards said gas exchanging membrane.
 25. A recipient according toclaim 24, wherein said plurality of bulges comprise studs.
 26. Arecipient according to claim 25, wherein said plurality of bulgescomprise matrix-like arranged in said hermetically sealed area.
 27. Arecipient according to claim 24, wherein said at least one aperture isprovided between said plurality of bulges.
 28. A recipient according toclaim 26, said recipient comprising a plurality of apertures in saidhermetically sealed area, said plurality of apertures being matrix-likearranged between said plurality of bulges.
 29. A recipient according toclaim 24, wherein said plurality of bulges are line-like bulges.
 30. Arecipient according to claim 24, wherein the bulges have a thickness inthe range of 0.1 mm to 5 mm.
 31. A recipient according to claim 11,wherein said spacing arrangement is provided by a raised edge aroundsaid aperture, said raised edge being provided at said outer side ofsaid flexible polymer wall in said hermetically hermetically sealedarea.
 32. A recipient according to claim 1, wherein said air chamberprovides an average distance between said gas exchanging membrane andsaid hermetically sealed part of said flexible polymer wall in the rangeof 0.1 mm to 10 mm.
 33. A recipient according to claim 1, wherein saidat least one aperture is a substantially circular aperture.
 34. Arecipient according to claim 1, wherein said at least one aperture has asurface area in the range of 0.18 mm² to 2.00 mm².
 35. A recipientaccording to claim 1, wherein said receipting is a bag or container. 36.A filter strip comprising a first surface and a second surface, saidfilter strip comprising an elongate flexible polymer material comprisingat least one opening, the filter strip comprising at least a first gasexchanging membrane allowing gas to pass from one of the first andsecond surface of the strip to the other of the first and second surfaceof the strip, said gas exchanging membrane being coupled to saidelongate flexible polymer material along a first sealing line, saidfirst gas exchange membrane covering said at least one opening.
 37. Afilter strip according to claim 36, wherein at least part of theflexible polymer material of the first surface of the filter strip issuitable for being sealed to a support, the said filter strip furthercomprising a spacing means for avoiding contact between the at leastfirst gas exchanging membrane and the support when the at least part ofthe flexible polymer material of the first surface of the filter stripis sealed to the support.
 38. A filter strip according to claim 37,wherein said filter strip further comprising an elongate flexiblepolymer sheet, said elongate flexible polymer sheet covering said atleast one opening and being sealed to said flexible polymer material atthe first side of the filter strip along a second sealing lineencompassing said at least one opening, said spacing means beingprovided between said elongate flexible polymer sheet and said at leastone gas exchanging membrane, said elongate flexible polymer sheet havingat least one aperture in the area of the elongate flexible polymer sheetencompassed by said second sealing line.
 39. A filter strip according toclaim 36, wherein the elongate flexible polymer material comprises Nopenings, N being more than one, the filter strip comprising N gasexchanging membranes, each allowing gas to pass from one of the firstand second surface of the strip to the other of the first and secondsurface of the strip, said gas exchanging membranes being coupled tosaid elongate flexible polymer material along N sealing lines, each ofsaid N gas exchange membranes covering one of said N openings.
 40. Apolymer sheet for providing polymer recipients, said polymer sheetcomprising a flexible polymer wall having a first outer surface, atleast one filter strip according to claim 36, at least part of theflexible polymer material of the first surface of the filter strip beingsealed to said outer surface of said flexible polymer wall by ahermetical seal along a sealing line, said sealing line defining ahermetically sealed area of said flexible polymer wall, said wallcomprising at least one aperture being provided in said hermeticallysealed area of said flexible polymer wall, said spacing means creatingan air chamber circumscribed by said hermetically sealed area, saidhermetical seal and said gas exchanging membrane.
 41. A polymer sheetfor providing polymer recipients, said polymer sheet comprising at leasta first flexible polymer wall having an outer surface, said polymersheet comprising at least one filter strip according to claim 38, atleast part of the flexible polymer material of the first surface of thefilter strip being sealed to said outer surface of said first flexiblepolymer wall by a hermetical seal along a sealing line, said sealingline extending along one of the elongate sides of said filter strip. 42.A polymer sheet for providing polymer recipients according to claim 41,said polymer sheet comprising a second flexible polymer wall having anouter surface, at least part of the flexible polymer material of thefirst surface of the filter strip being sealed to said outer surface ofsaid second flexible polymer wall by a hermetical seal along a sealingline, said sealing line extending along the other of the elongate sidesof said filter strip.
 43. The use of a recipient according to claim 1for cultivation of mushroom spawn or fungi.
 44. The use of a recipientaccording to claim 1 for containing powder-like substrate.